Continuous vacuum filter



Feb. 3, 1948. c. PORTER 2,435,235

commuods vAcUuu FILTER Filed Oct. 28, 1944 2 Sheets-Sheet 1 CIL4RLES L. PORTER INVENTOR.

ATTORIVEY Feb. 3, 1948. c, PORTER 2,435,235

commuous vAcUuu FILTER Filed Oct. 28, 1944 2 Sheets-Sheet 2 aux/ms L. PORTER.

uvmvron w. Mfifiw Arrommy III Patcnied Feb. 1948 m'rao STATES PATENT orrlcs 2.435.235 conrmnous vacuum: m'ran Charles L. Porter, Carlsbad, N. Mex. Application Ociober 2a, 1944, Serial No. seo,1so comma (or. 210-199) My invention relates to continuous vacuum filters of the rotary drum type and particularly to arrangements for controlling the flow of compressed air to facilitate the release of filter cake from the drum.

The continuous rotary vacuum filter is widely used for filtering operations such as are necessary in the purification or concentration of ores and similar compositions. These filters are particu-. larly useful for processes which require a washing operation with clear water following the initial removal of filtrate. The filter drum of these rotary filters is divided into a plurality of independent filter compartments and each compartment is connected alternately to a vacuum pump and to a compressed air supply, the vacuum collecting a filter cake as the drum rotates through a tank containing pulp and the filter cake being removed by a blast of compressed air after the filtrate has been drawn from it.

The valve control for effecting the various air circuit connections is conventionally arranged on one of the trunnions of the drum. and comprises a rotary disk valve arranged to connect each compartment in turn to the vacuum pump and later to the compressed air supply. Both the low pressure of the vacuum line and the high pressure of the compressed air line are handled by this same valve, and difliculties arise in maintaining these valves in continuous service. For this reason and to secure economical use of the compressed air the length of time during which the valve is subject to the high pressure of the compressed air line has been reduced by providing a spring biased valve in the air supply line and by actuating this valve intermittently to supply compressed air to the main valve only when it is required for the air blasting operation, The life of the main control valve is thereby prolonged but these spring biased valves have not been entirely satisfactory.

-Acc0rdingly it is an object of my invention to provide in a filter of the rotary continuous vacuum type an improved arrangement for controlling the supply of compressed air for facilitating the removal ofthe filter cake.

Further objects and novel features of my invention will become apparent as this description proceeds and the features of novelty which characterize my invention will be pointed out with particularity in the appended claims.

For an understanding of my invention reference may be had to the following description taken in connection with the accompanying drawings in which:

Fig. 1 is an end elevation view of a rotary filter embodying my invention:

Fig. 2 is a side elevation view of one end of the filter of Fig. 1;

Fig. 3 is an enlarged sectional side elevation of the compressed air valve employed with the filter of Fig. 1; i

Fig. 4 is' a sectional view on the line 4-H of Fi 3; and

. Fig. 5 is a sectional view on the line 5-5 of Fig.3.

Referring now to the drawing, the filter illustrated in Figs. 1 and 2 comprises a tank 6 provided with supporting ends i, only one of which is shown on the drawing. A filter drum 8 is rotatably mounted on a horizontal axis so that Continuous filters of this type. as is well known in the art, are provided with a plurality of independent filter compartments 'as "C" and D' arranged in succession about the circumference of the drum and covered with filter screens. As the drum rotates each compartment passes through the pulp in the tank while a rotary automatic control valve connects the compartment to a vacuum pump so that a. filter cake is collected on the screen. The vacuum is maintained so that the filtrate is drawn from the cake after the cake has emerged from the pulp, and if desi-rable, wash water is sprayed over the cake. Then the vacuum is shut off as the cake descends on the far side of the drum and a blast of compressed air is admitted to loosen the filter cake from the screen.

The details of the construction and arrangement of the filter compartments and of the vacuum pump and automatic control valve have not been illustrated as they are not necessary to an understanding of the present invention. The rotary automatic control valve for connecting the compartments successively to the vacuum pump line "V and compressed air supply line is arranged at the end of the trunnion 9 and is generally indicated by the letter A." This valve is provided with a control arm l3 to select the posiconnected and disconnected to the vacuum pump and connected to and disconnected from the 0031-.

pressed air supply line.

The filter cake which has been loosened by the blast of compressed air moves on the downwardly rotating side of the drum against a scraper ll which removes the cake from the filter screen and allows it to fall on a suitable conveyor or other receptacle (not shown).

In order to reduce the required capacity of the com-pressed air supply system and to avoid dimculties which have arisen when the automatic control valve is subject to full air pressur throughout the operation of the filter, a separate valve may be provided in the compressed air line, this valve being synchronized with the auto- 4 with its arms 22 in alinement with the openings 28 in the plate 22.

matic control valve to admit compressed air to the automatic control only when a compartment is in position to receive the blast of compressed air.

' In the filter illustrated, compressed air is conducted to the interior of the trunnions through a supply line It, and a control valve I8 is provided to admit the compressed air only at predetermined times. Heretoiore, valves biased to their closed position have been employed in the compressed air supply line, the valves being engaged successively and opened by equally spaced arms or projections on the trunnions such as indicated at H on the drawing. While these valves have avoided most of the difilcult es caused by the constant presence of compressed air at the automatic control valve, they have been subject to variable performance, and have required considerable attention and servicing with resultant shut-downs in order to maintain the filter in operation.

The valve l6, as shown in Figs. 3, 4 and 5 is a rotary type valve having a casing comprising end plates l8 and f8 and a cylindrical shell secured together by four longitudinal bolts 2| extending between the end plates outside the shell. A stationary transverse partition plate 22 is secured within the shell 20 and a complementary rotatable plate 23 is mounted on a shaft 24 in face engagemenet with the plate 22. The plates 22 and 23 are provided with corresponding radially extending elongated openings 25 and 28, re-

spectively; these openings being spaced at equal angles circumferentially of the plates. The plate 23 is slidable axially on the shaft 24 toward plate 22 but is keyed against rotation on the shaft by a key 21 formed on the shaft and fitting a slot in the plate.

The end' of the shaft within the casing is mounted in a suitable bearing assembly 28 in a recess in the plate 22 and the driven end of the shaft is mounted in a main ball bearing assembly 29 in the end plate IQ of the valve casing. The valve Plates 22 and 23 are maintained in sealing engagement by a compression spring 3!) surmounting'the shaft 24 and engaging the disk 23 and the bearing cover on the plate IS. The engaging faces of the plates 22 and 23 may be lubricated through a pressure connection 3i extending outside the shell 20 and arranged to conduct lubricant through the center of the plate 22 to the The valve II is mounted on the end support I adjacent the trunnions so that the driving arms 22 of the valve are in the path of the projections I! on the trunnion. The arms 23 and the projections I! are so arranged that each projection i1 when passing the wheel 22 engages an arm 22 and rotates the wheel through one quarter of a turn bringing the next arm 22 in position to be engaged by the next projection H. The projections are set so that the wheel 22 is turned to open the valve It only when a filter compartment is in position to receive a blast of compressed air, the projections being adjusted with reference to the automatic control valve in the trunnions so that they strike the star wheel 22 and move it to open the valve only when the automatic valve has shut oi the vacuum pump connection. The details of the arrangement for adjusting the positions of the series of projections "have not been illustrated in order to avoid complication of the drawing.

The valve, It is uniform in operation and provides an effective seal to prevent the admission of compressed air to the automatic control valve except when a blast is required. In this connection it will be noted that the air under pressure 'and entering the shell 20 from the top portion of the line II holds the valve plate 22 against the plate 22 when the valve is closed. On each movement of the star wheel the valve is open for the same length of time and there is substantially no variation in the blasts of air: this uniformity is insured since the speed of the drum is constant and hence the speed of movement of the valve [8 i consistently the same on each quarter rotation of the star wheel.

During the operation of the filter illustrated the tank 2 is continuously supplied with the pulp I .to be filtered. and the drum 8 is rotated at a seand the valve I6 is adjusted so that it is closed when the star wheel is not engaging a projection ll. As the drum rotates a filter cake is formed on each compartment under vacumn, and then as the filter compartment moves toward its position for release, one of the projections l'l engages the star wheel 22 and turns it through a quarter of a revolution to admit a blast of air at the selected time. This loosens the filter cake from the screen and thereafter the cake is renioved from the drum upon passing the scraper l Obviously the positions of the projections ll may be selected to open the valve ll at the desired time regardless of the time required to effect the complete quarter turn of the star wheel; it being evident that the valve is open during only a bearing 28 and the engaging surfaces between a the plates.

The valve it has been shown with four equally spaced openings in each of the plates 22 and '23 so that the valve is opened once every quarter revolution of the shaft 24. In order to actuate tinuous rotary drum filter and for insuring uniform and consistent operation of the compressed the valve a four armed star wheel 32 is provided air blast for looseninz the filter cake- I do not, therefore, desire my invention to be limited to the particular construction illustrated and described, and I intend by the appended claims to cover all modifications which fall within the spirit and scope or my invention.

What I claim and desire to'secure by Letters Patent is:

l. The combination with a continuous vacuum type filtering apparatus having a rotary drum provided with a plurality of filter compartments, and with which is associated control means for alternately connecting a vacuum conduit and an air pressure conduit with a filter compartment, of valve means for controlling flow through the air pressure conduit and comprising a rotatable valve member having conduit flow open and closed positions; means for moving the valve member to open and closed positions; and means mounted on said drum for actuating saidmoving means upon rotation of said drum, said valve member being moved to open position each time said air pressure conduit is connected to a filter compartment by said control means.

2. The combination with a continuous vacuum type filtering apparatus having a rotary drum provided with a plurality of filter compartments, and with which is associated control means for alternately connecting a vacuum conduit and an air pressure conduit with a filter compartment,

means mounted on said drum and rotatable there-' with for actuating said rotating means.

3. The'combination with a continuous vacuum type filtering apparatus having a rotary drum provided with aplurality of filter compartments and with which is associated a control means for alternately connecting a vacuum conduit and an air pressure conduit with a filter compartment, of valve means for controlling flow through the air pressure conduit and comprising a stationary memberhaving a plurality of circumferentially spaced radial ports and a rotary member having a plurality of similar complementary ports, said ports when in coinciding relation permitting fiow through the air pressure conduit to said control means, a star wheel connected to the rotatable valve member and having arms corresponding in position and number to the ports. and circumrerentially spaced actuating members connected to the drum for rotation with the drum about the drum axis for turning said star wheel and placing theports in coinciding relation each time the drum rotates through a predetermined angle.

4. The combination with a continuous vacuum type filtering apparatus having a rotary drum mounted on trunnions and provided with a pin-.-

. rality' or filter compartments with which is associated control means for alternately connecting a vacuum conduit and an airpressure conduit with a filter compartment, or valve means for controllin fiow throush the air pressure conduit to 1,835,796

and comprising a stationary valve member and a rotatable valve member each having equally spaced circumferentially positioned ports which register each time the rotatable member is turned through a predetermined angle, said ports when registering permitting fiowthrough said air conduit to said control means, a driving member connected to the rotatable member and having equally spaced radially extending actuating elements, and projections on the trunnion for cooperative engagement with the elements, said projections on the trunnions being so circumterentially spaced that a projection will engage an element and move the ports to register when the drum rotates through a predetermined angle, said registering positions of the ports occurring when the control means connects the air pressure conduit to a filter compartment.

5. The combination with a continuous vacuum type filtering apparatus having a rotary drum provided with a plurality of filter compartments and with which is associated a control means for alternately connecting a vacuum conduit and an air pressure conduit with a filter compartment, of valve means for controlling fiow through the air pressure conduit and comprising a stationary ,member and a rotatable'member having comple-.

mentary ports arranged to register to place said valve in open position at equally spaced angular positions throughout the rotation of said rotatable member, means, including a compression spring, for maintaining said members in sealing engagement, and means including actuating members connected to rotate with said drum for intermittently turning said rotatable member through the angle between adjacent ones oi said angular positions to move said valve to open position and thereby admit compressed air through said air pressure conduit to said control means for each predetermined position in the rotation of said drum.

6. Valve means for association with an air pressure conduit of a continuous vacuum type filterlug apparatus having a rotary drum provided with a plurality or filter compartments and with which is employed a control means for alternately connecting a vacuum conduit and the said air pressure conduit with a filter compartment, said valve means being positioned in the air pressure conduit ahead of the control means and comprising a stationary member having a plurality of circumferentially spaced ports and a rotary memher having a plurality of similar complementary ports, said ports when in registering relation permitting flow through the air pressure conduit, circumferentially spaced actuating elements mounted for rotation with the drum. anaotuating member connected to the rotatable valve member and having arms corresponding in position and number to the ports and adapted to be arranged for cooperation with. the actuating elements so that the rotary member is periodically moved and the ports placed in register as the drum rotates.

CHARLIE L. PORT nm-aannoascmm The following references are or file of this patent:-

- Lee June 2''. 10M McOaskell Dec. 8. 1081 reeordinthe' 

